--Disease Characteristics-- Histologically proven newly diagnosed stage I, II, or resectable IIIA primary breast cancer Scheduled to receive chemotherapy No distant metastases --Prior/Concurrent Therapy-- Biologic therapy: Not specified Chemotherapy: See Disease Characteristics No concurrent neoadjuvant chemotherapy Endocrine therapy: No concurrent thyroid medication Radiotherapy: No concurrent radiotherapy Surgery: See Disease Characteristics No prior oophorectomy Other: No concurrent alternative medicines alone No concurrent participation in dietary and/or exercise weight loss programs --Patient Characteristics-- Age: 18 to 80 Sex: Female Menopausal status: Premenopausal or postmenopausal Performance status: Not specified Life expectancy: Not specified Hematopoietic: Not specified Hepatic: Not specified Renal: Not specified Other: No physical or mental disability that would preclude completing questionnaires No prior or concurrent diabetes mellitus No prior hypothyroidism or hyperthyroidism